U.S. patent number 5,303,094 [Application Number 07/936,147] was granted by the patent office on 1994-04-12 for apparatus for recording and/or reproducing digital and analog magnetic tape signals with a/d and d/a converters.
This patent grant is currently assigned to U.S. Philips Corporation. Invention is credited to Yasuo Kato, Gerardus C. P. Lokhoff.
United States Patent |
5,303,094 |
Kato , et al. |
April 12, 1994 |
Apparatus for recording and/or reproducing digital and analog
magnetic tape signals with A/D and D/A converters
Abstract
In an arrangement for reproducing standard analog audio compact
cassettes and digital compact cassettes is provided with an analog
output terminal (9) for supplying an analog audio signal obtained
from reproducing a digital audio signal from a digital compact
cassette, or an analog signal from a standard compact cassette. The
analog reproducer (28) is coupled to the analog output terminal (9)
via an A/D converter (20) and a D/A converter (13). A further
measure that can be used separate or in combination with the
previous measure, is that a digital output terminal (23) is
provided and that the output of the analog reproducer is coupled to
the digital output terminal (23) via an A/D converter (13).
Inventors: |
Kato; Yasuo (Kanagawa,
JP), Lokhoff; Gerardus C. P. (Eindhoven,
NL) |
Assignee: |
U.S. Philips Corporation (New
York, NY)
|
Family
ID: |
27341877 |
Appl.
No.: |
07/936,147 |
Filed: |
August 26, 1992 |
Foreign Application Priority Data
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|
|
|
|
Aug 30, 1991 [JP] |
|
|
3-76801 |
Aug 30, 1991 [JP] |
|
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3-76802 |
Aug 30, 1991 [JP] |
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|
3-76803 |
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Current U.S.
Class: |
360/32; 360/61;
G9B/15.017; G9B/20; G9B/5.019 |
Current CPC
Class: |
G11B
5/00878 (20130101); G11B 20/00 (20130101); G11B
15/125 (20130101) |
Current International
Class: |
G11B
15/12 (20060101); G11B 5/008 (20060101); G11B
20/00 (20060101); G11B 005/00 (); G11B 005/09 ();
G11B 015/12 () |
Field of
Search: |
;360/32,60,61,63,64,13,15 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Hajec; Donald
Assistant Examiner: Wamsley; Patrick
Attorney, Agent or Firm: Fox; John C.
Claims
We claim:
1. An apparatus for receiving a magnetic tape accommodated in a
cassette, the apparatus comprising a digital-signal reproducing
part, an analog-signal reproducing part, an analog-signal output
terminal and first switching means for selectively coupling the
analog-signal output terminal to an output of the analog-signal
reproducing part and via a D/A converter to an output of the
digital-signal reproducing part, characterized in that the
apparatus further comprises an A/D converter and in that the
apparatus is adapted to couple the output of the analog-signal
reproducing part to the analog-signal output terminal via said A/D
converter and said D/A converter, in the situation when the first
switching means is switched such so as to provide the coupling
between the output of the analog-signal reproducing part and the
analog-signal output terminal.
2. The apparatus as claimed in claim 1, characterized in that it
comprises a digital signal recording part having an input and an
output, a digital-signal input terminal, a digital-signal output
terminal, an analog-signal input terminal, second switching means
for selectively coupling the digital-signal input terminal and the
analog-signal input terminal via the A/D converter to the input of
the digital-signal recording part.
3. The apparatus as claimed in claim 2, characterized in that third
switching means is provided so as to enable a selective coupling of
an input of the A/D converter to the analog-signal input terminal
and the output of the analog-signal reproducing part.
4. The apparatus as claimed in claim 3, characterized in that the
digital-signal output terminal is selectively coupled via the first
switching means to the output of the A/D converter and to the
digital-signal reproducing part.
5. The apparatus as claimed in claim 2, characterized in that the
digital-signal output terminal is selectively coupled via the first
switching means to the output of the A/D converter and to the
digital-signal reproducing part.
6. An apparatus for receiving a magnetic tape accommodated in a
cassette, comprising a digital-signal reproducing part, an
analog-signal reproducing part, an analog-signal output terminal, a
digital-signal output terminal, first switching means for
selectively coupling the analog-signal output terminal to an output
of the analog-signal reproducing part and via a D/A converter to an
output of the digital-signal reproducing part, characterized in
that the apparatus further comprises an A/D converter and that
second switching means are provided to selectively couple the
digital-signal output terminal to the output of the analog-signal
reproducing part via said A/D converter.
7. The apparatus as claimed in claim 6, characterized in that third
switching means are provided so as to selectively couple the
digital-signal output terminal to the output of the digital-signal
reproducing part and to the output of the A/D converter.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for receiving a magnetic
tape accommodated in a cassette, comprising a digital-signal
reproducing part, an analog-signal reproducing part, an
analog-signal output terminal and first switching means for
coupling the analog-signal output terminal either to an output of
the analog-signal reproducing part or via a D/A converter to an
output of the digital-signal reproducing part.
Such an apparatus, described in EP 381 266 A1 (PHN 12.816 C), is
capable of reproducing either analog-audio signals from a standard
audio compact cassette or digital-signals from a digital compact
cassette (DCC). Such apparatuses can be used in car radios, where
preferably only the analog or digital reproduction facilities of
the apparatus is required.
Apparatuses for home-use are however additionally provided with a
digital recording facility, so as to record audio signals, in
analog or digital form, on the record carrier included in a digital
compact cassette. In that case, an A/D converter is provided for
converting the analog audio signal into a digital audio signal so
as to enable recording on a digital compact cassette.
SUMMARY OF THE INVENTION
The invention aims at simplifying the production of the various
apparatuses, such as, applied in a car radio or in a DCC
home-recorder.
To that purpose, the apparatus in accordance with the invention is
characterized in that the apparatus further comprises an A/D
converter and that the apparatus is adapted to couple the output of
the analog-signal reproducing part to the analog-signal output
terminal via said A/D converter and said D/A converter, in the
situation when the first switching means are switched so as to
provide the coupling between the output of the analog-signal
reproducing part and the analog-signal output terminal.
The invention is based on the following recognition. Manufacturers
of apparatuses as previously described aim at reducing production
costs by developing identical circuit constructions for various
types of apparatuses. More specifically in apparatuses provided
with a digital-signal recording and a reproduction part and an
analog-signal reproduction part, such apparatus is provided with an
A/D converter for converting the analog signal supplied to the
apparatus into the digital domain so as to enable the signal to be
recorded.
If, in such an apparatus, the output of the analog-signal
reproducing part is coupled to the input of the A/D converter, and
subsequently coupled via the D/A converter to the analog-signal
output terminal, an analog selection switch can be left out. This
lowers the production costs.
Selection between the signal reproduced by the analog-signal
reproduction part and the signal reproduced by the digital-signal
reproduction part can now be realized by the monitor switch, which
is already normally present between the A/D converter and the D/A
converter. Further, such a monitor switch, which is incorporated in
the digital domain, can be realized more easily than analog
switches.
As an additional advantage, coupling the output of the
analog-signal reproducing part to the input of the A/D converter,
offers the possibility to supply the analog signal after A/D
conversion, to a digital-signal output terminal.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described in more detail, with reference
to the drawing in which
FIG. 1 shows a schematic diagram of a first embodiment of the
invention, and
FIG. 2 shows a schematic diagram of a second embodiment of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 diagrammatically shows a circuit of a cassette tape recorder
according to an embodiment of the present invention. In FIG. 1, an
analog signal input terminal 1, a recording level adjuster 2, an
analog signal output terminal 9, an amplifier 10, a head-phone
terminal 11, a digital interface 14, a digital signal processor 15,
a recording amplifier 16, a recording head 17, a reproduction head
18, a reproduction amplifier 19, a digital-to-analog converter 20,
a buffer amplifier 21 and a digital signal output terminal 23.
Shown at 28 is an analog signal reproduction head which is
connected to a reproduction amplifier 29. This amplifier is
connected to the noise reduction circuit 25.
A signal change-over switch 33 is interposed between the input of
the analog-to-digital converter 13 and the output of the noise
reduction circuit 25. This switch 33 connects the noise reduction
circuit 25 to the analog-to-digital converter 13 when a terminal c
thereof is brought into contact with a terminal a of this switch,
and connects the analog-to-digital converter 13 to the recording
level adjuster 2 when the terminal c is brought into contact with
another terminal d of this switch.
The operation of the above circuit will now be described. It is
assumed here that the switch element 33 is now positioned so as to
connect the terminals d and c with each other. In this case, an
analog signal supplied to the analog signal input terminal 1 is
subjected to a recording level adjustment at the recording level
adjuster 2 and is fed to the digital interface 14 after converted
into a digital signal in the analog-to-digital converter 13. The
digital signal is converted into a standardized digital signal by
this digital interface and is then supplied to the digital signal
processor 15 wherein the signal is subject to necessary signal
processing such as data conversion processing, interleaving and
modulation processing. The thus processed digital signal is fed to
the recording amplifier 16 and then recorded on a digital compact
cassette tape through the recording head 17.
On the other hand, a digital signal fed to the digital signal input
terminal 12 is directly supplied to the digital interface 14, which
is then signal processed in the same way as described above and
recorded on a digital compact cassette tape. To that purpose, the
interface 14 comprises switching means so as to select either the
analog or the digital input signal for recording.
The operation of this circuit in the reproduction mode will now be
described.
(A) The case where a digital signal is to be outputted from the
digital signal output terminal when reproducing an analog signal or
a digital signal.
(1) When reproducing an analog signal, the switch 33 is positioned
so as to connect the terminals a and c with each other. An analog
signal detected by the reproduction head 28 from an analog compact
cassette tape is supplied through the reproduction amplifier 29,
the noise reduction circuit 25 and the signal change-over switch 33
to the analog-to-digital converter 13. The reproduced analog signal
is converted into a digital signal in this converter and fed
through the digital interface 14, the buffer amplifier 21 and the
transformer 22 to the digital signal output terminal 23, from which
the digital signal is supplied to an external device.
(2) When reproducing a digital signal, a digital signal detected by
the reproduction head 18 from a digital compact cassette tape is
fed through the reproduction amplifier 19, the digital signal
processor 15, the digital interface 14 and the buffer amplifier 21
to the digital signal output terminal 23, from which the reproduced
digital signal is supplied to an external device.
Thus, in either of the analog and digital reproduction modes, the
reproduced signal can be outputted through the single signal
circuit from the digital signal output terminal 23 as a digital
signal.
(B) The case where an analog signal is to be outputted from the
analog signal output terminal when reproducing an analog signal or
a digital signal.
(1) When reproducing an analog signal, the switch 33 is positioned
so as to connect the terminals a and c. An analog signal detected
by the reproduction head 28 from an analog compact cassette tape is
supplied through the reproduction amplifier 29, the noise reduction
circuit 25 and the signal change-over switch 33 to the
analog-to-digital converter 13 in which the reproduced analog
signal is converted into a digital signal. This digital signal is
fed through the digital interface 14 to the digital-to-analog
converter 20 wherein the digital signal is converted into an analog
signal, which signal is outputted from the analog signal output
terminal 9.
(2) When reproducing a digital signal, switching means are provided
so that a digital signal detected by the reproduction head 18 from
a digital compact cassette tape and fed through the reproduction
amplifier 19 and the digital signal processor 15 is applied to the
digital-to-analog converter 20 wherein the digital signal is
converted into an analog signal which is outputted from the analog
signal output terminal 9.
Thus, in either of the analog and digital reproduction modes, the
reproduced signal can be outputted through the single signal
circuit from the analog signal output terminal 9 as an analog
signal.
With this embodiment, in either of the analog and digital
reproduction modes, a digital signal can be outputted from the
digital signal output terminal 23 and an analog signal can be
outputted from the analog signal output terminal 9. Therefore, when
connecting this recorder to an audio amplifier the connection can
be achieved by employing only either the analog signal circuit or
the digital signal circuit. Thus, the connection is very
simple.
In the above connection, since one of the analog and digital signal
circuits is used as a common signal circuit in either of the analog
and digital reproduction modes, there will be no difference in
sound quality due to the kind of signal circuit.
FIG. 2 shows the apparatus more schematically. More specifically,
all the switching means are shown more clearly. Switching means 40
is present so as to select either the digital input signal present
at the input 12 or the digital output signal of the A/D converter
13. The switching means 41 is provided so as to select either the
reproduced digital signal from the digital reproduction part
including the head 18, or the digital output signal of the A/D
converter 13.
It is to be noted here that the digital reproducing and recording
part 15, 16, 17, 18 and 19, need not necessarily be provided with a
separate recording head 17 and a separate reproducing head 18. The
recording head 17 and the reproducing head can be combined into one
recording/reproducing head.
Further, when applying the invention in an apparatus for use in a
car radio, normally the digital recording facility will not be
present. This means for the embodiment of FIG. 2 that the elements
with reference numeral 1, 12, 17, 23 and 40, can be left out and
that the switch 33 should be replaced by an electrical
interconnection between a and c.
It is evident that, where appropriate, the apparatus can be
provided with an analog-signal recording part, so as to enable the
recording of an analog-signal applied to the analog-signal input
terminal, or a digital signal after D/A conversion.
* * * * *